What all would have to be done to go from a 4.8 to a 5.3 in a 2000 Silverado. I have thought about when my motor goes out just replacing it and just curious if I could put a 5.3 in with out many problems.

whole new wiring harness and PCM. its not worth the labor involved.

I figured it might be a big pain in the arse.

shouldn't be a problem at all. dont see a big difference in
horse power (15) back then between the two.. pretty much harness's
and all componants are the same. work on em every day and have
not noticed any external differences at all.. I can check on soft
ware issues when back at work mon if you like...
4.8-5.3-6.0 externally same. just alumn 4.8/5.3 cast iron 6.0

Trade before it go's.the newer one has such a better suspenion too. I'm glad I traded 2001 4.8 to 08 5.3. I pull a trailer everyday and there is a big difference. wish I could pull the the boat more.

Yea but my 2000 is paid for.

I hear you. It was a tough call for me too. early 08 they were giving them away. I paid less for my 08 than my 01 and got alot more truck

May want to check out ls1tech.com and see what all is involved for putting a 6.0liter or a 5.7(ls-1, ls-6, or other LS based motor) into your truck. It would be a big jump from the 4.8